Chronic Lisuride Hydrogen Maleate Administration Enhances Muscarinic Receptor Binding in Senescent Rat Brain

Changes in the regional density of muscarinic-1 (M₁) receptors and the effect of lisuride hydrogen maleate on these changes were studied in senescent rat brain by in vitro autoradiography. In young adult controls, M₁ receptor binding was most dense in the striatum and hippocampus, followed by the cerebral cortex and amygdala. Binding to M₁ receptors was markedly lower in these areas of the senescent brain compared with the young adult brain. These decreases were reversed by intraperitoneal administration of 50 μg/kg·day lisuride for 14 days. The present results indicate that the therapeutic efficacy of lisuride depends on normalization of not only monoamine systems but also acetylcholine systems.